1. Field of the Invention
The present invention relates to the use of a compound, in particular of a derivative of phosphorous acid, especially of fosetyl-Al, for treating plants for the purpose of improving the bud quality thereof.
2. Description of Related Art
Fosetyl-aluminum or fosetyl-Al is a known fungicidal compound. Its chemical name is aluminum ethyl hydrogen phosphonate whose chemical structure is the following:

Moreover, the bactericidal activity of fosetyl-Al is also known, especially from European patent application EP-249566.
The problem of flower bud dieback is not new and has already been examined for a long time. For many years, the phenomenon of flower bud dieback, especially on pear trees, has been observed. Such a phenomenon can, within a few years, dramatically reduce the productivity of fruit trees. This phenomenon may also lead to the digging up or destruction of the affected plants in order to avoid the propagation of the organisms implicated.
The origin or the reasons for this phenomenon are not known. It could be linked to bacterial infections, for example caused by Pseudomonas syringae pv. syringae or alternatively fungal infections, for example caused by Alternaria alternata. This phenomenon could also be explained by a late availability of nitrogen which stimulates the physiological activation of flower buds that is not externally perceptible and that could make them more vulnerable to such a flower bud dieback.
Furthermore, the frequency of the flower buds that have died back can vary considerably from year to year and the youngest plants may be more sensitive than the older plants for the same cultivar, the phenomenon may vary from one variety to another. During the season, the climate may also have an influence on the phenomenon; a hot period at the end of the autumn season followed by a period of heavy frost has often been considered as a decisive element which may lead to the dieback of flower buds. It may also happen that the flower buds are not sufficiently in winter dormancy at the time of the first frosts. The internal tissue of the flower buds can thus be damaged and then infected.
The damage caused by dieback of buds is often only visible several months after having been initiated, or even the following year at the time of flowering, of fruit formation or of harvest. It is then impossible to undertake the least treatment aimed at reviving the situation.
Some antibiotic or antibacterial products, such as streptomycin, have been used for combating this phenomenon. Such plant protection uses of products are now limited as far as possible, or even banned, especially because of problems of resistance in the phytopathogenic bacteria which are generated by massive land spreading of such antibiotic or antibacterial products. Such problems of resistance could be transferred to bacteria that are pathogenic for animals or even humans.